Dec 8th 2010, 8:05:40
edit: actually, your wording seems imprecise
Do you mean that there must exist a subset, or that there possibly could exist a subset?
It's a trivial question if you mean that there possibly could exist a subset, so I'm guessing you mean that there must exist a subset no matter what groupings you use.
Do you mean that there must exist a subset, or that there possibly could exist a subset?
It's a trivial question if you mean that there possibly could exist a subset, so I'm guessing you mean that there must exist a subset no matter what groupings you use.